1. Field of the Invention
The invention relates in general to a method for stacking cut cardboard pieces, and to an apparatus for carrying out this method.
In a corrugated cardboard plant, an automatic delivery system has the task of stacking, for example on a vertically movable table, sheets of corrugated cardboard which have been cut to a specific format. Transport from the transverse cutter to the stacking device is effected by conveyor belts on which the sheets lie overlapping one another in the manner of scales. This overlap is effected due to the fact that the conveyor belts run more slowly than the arriving cardboard web.
The stack changing is effected in that the completed stack is driven out laterally and then the stacking device, for example the vertically movable table, is repositioned afresh. Since stack changing should take place without the speed of production of the plant being reduced, a gap must be formed within the flow of overlapping sheets in order to make the necessary time for the stack change.
2. Description of the Prior Art
It is already known for this purpose to block up the arriving flow of corrugated cardboard sheets. Blocking up can be effected by a blocking flap which is hinged down from above, or by a stop bar which is raised between two conveyor belts. Moreover it is possible to stop one of the belts while the subsequent belts continue to run with unchanged speed. The gap in the flow of overlapping sheets is produced by the speed difference of two successive belt lengths.
All the known possibilities have the disadvantage that irregular overlapping of the sheets occurs due to blocking up. As a result of different friction conditions, following sheets are pushed one over the other; this has the consequence that troubles arise in stack formation. During blocking up, lateral deviation of individual sheets can occur, which does not render possible clean stack formation. If several stacks are being formed side by side at the same time a mutual intermeshing of the stacks occurs which makes the separation of the stacks difficult and involves considerable interference with the progress of the work.